Film forming substances (FFS), including film forming amines (FFA) and other proprietary non-amine based FFS, are increasingly used in steam and HRSG cycles to reduce corrosion during operation and, especially, during shutdown and layup. In a January 27, 2026, CCJ-hosted webinar, the IAPWS Power Cycle Chemistry (PCC) committee explained what current guidance supports, why results vary from site to site, and how plants can reduce risk when evaluating these products.
Presenters: David Addison (Thermal Chemistry Ltd), Wolfgang Hater (H2O Training & Consulting), Barry Dooley (Structural Integrity).
Read on for a full report on the webinar. For those looking for more details, see the recording below and download the presentations slides here.
A consistent theme ran through the session: FFS is a supplement to a well-controlled base chemistry program, not a substitute for it. The presenters emphasized that deposit condition and corrosion-product transport must be understood before dosing begins, because several adverse outcomes reported in the industry are linked to applying FFS into cycles already trending toward repeat chemistry issues.
Addison first outlined IAPWS and the PCC committee’s role in developing technical guidance documents intended to translate research and field lessons into practical direction for power producers. He noted that the webinar focuses on application fundamentals, monitoring considerations, and, importantly, the risk controls IAPWS recommends before and after an FFS change.
There are two Technical Guidance Documents (TGD) freely available on the subject at the IAPWS website (www.IAPWS.org).
- Application of Film Forming Substances in Fossil, Combined Cycle, and Biomass Power Plants
- Application of Film Forming Substances in Industrial Steam Generators
FFS and where it fits in cycle chemistry
Hater defined FFS as an online and offline corrosion inhibitor that adsorbs on metal or oxide surfaces. These organic compounds are applied at low concentrations; volatility and steam transport depend on the specific molecule and formulation.
The webinar differentiated two common approaches:
- Supplemental dosing of an FFS while continuing a base program (for example, AVT, OT or PT).
- “Full treatment” packages in which the FFS is blended with other components intended to provide an entire treatment approach.
Terminology matters: FFA versus FFP
The presenters stressed that many published studies and field analytics focus on film forming amines (FFA), while film forming products (FFP) may be non-amine proprietary formulations with limited molecule-specific information in the open literature (Fig 1). That gap affects both risk screening and the plant’s ability to monitor what is actually circulating in the cycle.
Common mechanism model
Hater described a widely used conceptual model: a hydrophilic portion of the molecule anchors to the surface and a hydrophobic portion orients outward, creating a more hydrophobic interface. The practical goal is reduced metal water contact, which can reduce corrosion, particularly during shutdown and layup.
The presenters cautioned against treating hydrophobicity as proof of protection. Contact-angle and droplet observations can be misleading, and hydrophobic response alone does not confirm film integrity, coverage, or durability in all parts of the cycle.
Residuals, surface confirmation, decomposition impacts
Because a portion of the applied product adsorbs on surfaces, water-phase residual does not directly quantify surface coverage. Monitoring typically combines conventional cycle-chemistry indicators with residual measurement and, when warranted, surface confirmation methods. For FFA, the webinar discussed established analytical approaches based on Bengalrose and noted that more definitive surface verification can be performed with specialized laboratory techniques.
The presenters also noted that film-forming organics can decompose in hotter areas of the cycle, creating species such as ammonia and low-molecular-weight organic acids that can influence steam purity indicators. Practical implication: plants should anticipate these effects and manage them within established steam and water chemistry control limits.
Dosing location, operational cautions
The session supported automated dosing at typical condensate or feedwater locations, with rate tied to flow. The presenters emphasized conservative dosing and avoiding overdosage. They also advised confirming compatibility with materials and elastomers in the dosing system, and ensuring product constituents do not create unacceptable risk for turbine contamination if non-volatile components are present.
Benefits observed in service
Dooley summarized benefits frequently reported in combined-cycle and fossil applications:
- Lower iron transport in feedwater and condensate, with copper reductions often present in mixed-metallurgy plants.
- Improved shutdown protection on water-touched surfaces.
- Hydrophobic surface response that may be consistent with filming, but is not by itself proof of protection.
He also flagged an important limitation: film formation and protection on steam-touched surfaces remain questionable, because oxide growth on steam surfaces is not controlled in the same way by cycle chemistry.
Pre-application screening
A large portion of the webinar focused on adverse experiences reported in the industry when FFS are applied without understanding baseline conditions. Dooley listed outcomes that have been associated with poorly controlled application in some plants: increases in internal deposits, under-deposit corrosion and tube failures, gel-like deposits in drums and non-heat-transfer areas, turbine deposits, and plugging of strainers and filters.
Cleaning effects
Hater noted that some FFS products appear to “clean” by loosening porous oxide or mobilizing particulate, which can reduce transport after the initial period. The risk is that mobilized material can redeposit, accumulate as gels or agglomerates, or contribute to under-deposit corrosion in susceptible HRSG and boiler sections. The practical message is that deposit condition must be assessed before dosing begins; referred to as a Section 8 review as delineated in the IAPWS TGD.
Evaporator deposits, tube failure risk
Dooley presented HRSG HP evaporator deposits and tube failures that occurred after application without adequate up-front review. He emphasized that deposit loading and deposit character in these circuits should be assessed using IAPWS tools before any FFS decision. He also noted that some recent failures suggest mechanisms that merit further research and broader industry sharing (Fig 2).
ACC FAC: sometimes improved, not guaranteed
The webinar highlighted air-cooled condensers as a special case because two-phase FAC at tube entries can be visually tracked and indexed. Dooley provided an example in which an FFS program aligns with improved ACC indicators, while also stressing that many cases exist where neither FFA nor FFP arrests ACC FAC. Plants should treat claims of universal ACC improvement with caution and rely on site-specific monitoring (Fig 3).
Baseline, screening, verification
The presenters repeatedly framed FFS as an engineered change that should be implemented with defined objectives, staff training, and clear verification methods. They described “Section 8” as a structured path to reduce risk and to determine whether an FFS program is delivering value.
Key elements include:
- High quality corrosion product monitoring. Methods must include full digestion and detection limits suitable to resolve meaningful improvements.
- Achievable iron targets. Total iron levels should be compared to “achievable” benchmarks for the plant’s treatment approach and configuration (including ACC units). Values above benchmarks indicate repeat cycle chemistry situations that require correction before adding FFS.
- Flex-operation tools. For frequently started units, the webinar describes tracking iron decay during startup and comparing performance to an IAPWS decay map.
- Deposit screening. For HRSG HP evaporators, deposit loading should be assessed and compared to IAPWS deposit mapping guidance. Plants in a repeat cycle chemistry condition should not proceed with FFS until underlying issues are corrected. It was also shown that deposit analyses are equally applicable for fossil plant waterwalls (Fig 4).
Practical takeaways for owner/operators
The webinar’s message can be summarized as: FFS can provide benefits when used as part of a disciplined chemistry program, and they can increase risk when applied into cycles with unmanaged transport and deposits.
A practical checklist from the session:
- Optimize base chemistry first, then evaluate FFS as a supplement.
- Establish baselines for iron transport, deposit condition, and key chemistry parameters before dosing.
- Dose conservatively, avoid overdosage, and use fit-for-purpose analytics for residuals and (when needed) surface confirmation.
- Use IAPWS screening tools, including achievable iron targets, flex-operation indicators, and HRSG and boiler deposit assessment, before committing to full-scale application.
- If switching products, avoid mixing formulations and manage the changeover methodically.
Much research is still needed to fully understand FFS with particular emphasis on FFP. IAPWS will shortly publish an IAPWS Certified Research Need (ICRN) which delineates the main research needs. Contact Barry Dooley (bdooley@structint.com), Wolfgang Hater (wolfgang.hater@t-online.de), and David Addison (david.addison@thermalchemistry.com) to participate. CCJ
